Pancratic systems are utilized wherever a change of the magnification (also of the zoom) is wanted.
Reflections caused by glancing incident light present a special constructive problem because of the high optical performance specifications for optical apparatus. This applies especially to pancratic systems wherein holders are guided and moved in a lubricated bore because reflections are clearly visible in such systems under specific conditions.
U.S. Pat. No. 3,441,339 discloses a photoobjective wherein a lens is fixedly mounted in a lens holder tube. This lens holder tube is guided in an inner tube of the objective tube via three discrete holding bodies. These bodies have a relatively large spacing with respect to each other. In this connection, reference can be made to FIG. 1 of U.S. Pat. No. 3,441,339.
U.S. Pat. Nos. 4,322,150 and 4,448,496 disclose a zoom objective wherein an inner tube body is guided via four pins in another inner tube body having four recesses. Here, reference can be made to FIGS. 2 and 3 of U.S. Pat. No. 4,322,150 and FIGS. 11 and 12 of U.S. Pat. No. 4,448,496.
Swiss Patent 492,991 discloses an objective having a changeable focal length wherein the lens holder has three threaded lugs which are guided in three slots of an inner tube as shown in FIGS. 5 and 6 of this patent.